Anatomy of pain

Grimacing, we flinch when we see someone accidentally hit their thumb with a hammer. But is it really pain we feel? Researchers at the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig and other institutions have now proposed a new theory that describes pain as a multi-layered gradual event which consists of specific pain components, such as a burning sensation in the hand, and more general components, such as negative emotions. A comparison of the brain activation patterns during both experiences could clarify which components the empathic response shares with real pain.

Imagine you're driving a nail into a wall with a hammer and accidentally bang your finger. You would probably injure finger tissue, feel physical distress, focus all your attention on your injured finger and take care not to repeat the misfortune. All this describes physical and psychological manifestations of "pain" -- specifically, so-called nociceptive pain experienced by your body, which is caused by the stimulation of pain receptors.

Now imagine that you see a friend injure him or herself in the same way. You would again literally wince and feel pain, empathetic pain in this case. Although you yourself have not sustained any injury, to some extent you would experience the same symptoms: You would feel anxiety; you may recoil to put distance between yourself and the source of the pain; and you would store information about the context of the experience in order to avoid pain in the future.

Previous studies have shown that the same brain structures -- namely the anterior insula and the cingulate cortex -- are activated, irrespective of whether the pain is personally experienced or empathetic. However, despite this congruence in the underlying activated areas of the brain, the extent to which the two forms of pain really are similar remains a matter of considerable controversy.

To help shed light on the matter, neuroscientists, including Tania Singer, Director at the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, have now proposed a new theory: "We need to get away from this either-or question, whether the pain is genuine or not."

Instead, it should be seen as a complex interaction of multiple elements, which together form the complex experience we call "pain". The elements include sensory processes, which determine, for example, where the pain stimulus was triggered: in the hand or in the foot? "The decisive point is that the individual processes can also play a role in other experiences, albeit in a different activation pattern," Singer explains.

Thanks to the fact that our brain deals with these components in parallel, we can process various unpleasant experiences in a time-saving and energy-saving manner.